I think Froch. Talk about a tough/physical fight. Froch was naturally a little bigger and he had the better chin imo. Pavlik didn't really figjt anyone of note above 160 except for BHOP at a 170 pound catchweight and he looked terrible in that fight but then again, Hopkins made a lot of good fighters look bad. I think Pavlik stays upright but loses a UD to the very physical Froch.
Froch by SD/UD or late TKO after accumulation of damage in an absolute war. Just think Froch is too big, too strong and just a tad more durable. Would likely be a FOTY candidate though. Pity Pavliks prime was so short to be honest.
Taylor boxed Froch up but got stopped. Pavlik's a better boxer than Taylor with a better chin. However, Kelly couldnt carry himself at 168lbs very well. I remember his only fight at SMW with Will Rosinsky, an NYC firefighter if i recall correctly, Pavlik couldn stop him. After the fight he basically said in the post fight interview that he didn't have it at 168.